Compact press and pellet plunger

ABSTRACT

A modified compaction press having a cylinder and piston mounted below a pressure providing means, wherein relatively small amounts of a particulate sample can be subjected to a pressure in the range of 15,000 to 30,000 p.s.i.; the modification comprising a plunger movably positioned in the center portion of a bottom seal means of the press cylinder. The plunger provides a means for in situ breaking of compressed pellet or pill before subsequent repressing in the same cylinder cavity.

United States Patent Roland Feb. 5, 1974 [54] COMPACT PRESS AND PELLETPLUNGER 3,274,303 9/1966 Muller 425/412 X [751 Inventor: Charles Roland,Toledo, h iiili 251332 -223237.111:3::...........::::::::::: iii/3??Phillips Petroleum Company, Washington, DC.

O[22] Filed: May 4, 1972 [21] Appl. No.: 250,294

[73] Assignee:

US. Cl 425/412, 425/355, 425/438, 425/444, 425/317 Int. Cl. B29c 3/00Field of Search... 425/406, 412, 355, 317, 438, 425/444, 801, 804, 808

References Cited UNITED STATES PATENTS 6/1912 Haefely 425/406 1/1905Breitschwerth 425/438 X Primary Examinere-RobertL. Spicer, Jr. Attorney,Agent, or Firm-Quigg & Oberlin [57] ABSTRACT A modified compaction presshaving a cylinder and piston mounted below a pressure providing means,

wherein relatively small amounts of a particulate sample can besubjected to a pressure in the range of 15,000 to 30,000 psi; themodification comprising a plunger movably positioned in the centerportionof a bottom seal means of the press cylinder. The plungerprovides a means for in situ breaking of compressed pellet or pillbefore subsequent repressing in the same cylinder cavity.

3 Claims, 1 Drawing Figure 1 COMPACT PRESS AND PELLET PLUNGER Thisinvention relates to a compaction press which is suitable for subjectingrelatively small amounts of granular or powder form material to highpressures. In another aspect, this invention relates to a modifiedcompaction press having a plunger movably positioned in the centerportion of a bottom seal means of the press cylinder thereby providing ameans for in situ breaking of pressed pellets. In another aspect, thisinvention relates to apparatus for the repeated subjection of carbonblack particles to a pressure in the range of from 15,000 to 30,000 psi.In a further aspect, this invetion relates to apparatus which isdesigned to repeatedly compress carbon black particulate samples andbreak the resulting pellets prior to subjecting the carbon black to theASTM D2414-67T dibutyl phthalate absorption test.

For many years, those in the carbon black industry and those in therubber industry have utilized the ASTM D24l4-67T DBP absorption test todetermine the structure of carbon black. Structure refers to the forceresponsible for agglomeration, that is particle-toparticle forces.Because of the particulate nature of carbon, it is necessary to measurethe effects of these agglomerative forces by indirect methods. The ASTMprocedure mentioned above has been widely accepted as a standard test bythe carbon black and rubber industries in determining structure, thisspecification having become critical for both producers of carbon blackand those who use carbon black, especially in the fabrication of naturaland synthetic rubber automobile tires. The basic importance of thestructuralproperty of carbon black in rubber compounding results fromthe fact that it is this property which determines the reduction innerve of an elastomer when the two are mixed together. Thereduction innerve reduces shrinkage when an elastomer is extruded through a die;hence, one measure of the effect of the structure upon the elastomer isextrusion shrinkage or die swell.

It was reported by the American Chemical Society, Division of RubberChemistry Meeting, Sept. 13-16, 1966, at New York, N.Y., in a paper byR. E. Dollinger, R. H. Kallenberger and M. L. Studebaker, entitled TheEffect of Carbon Black Densification on Structure Measurements andRubber Properties that the test results obtained by conventional methodsto determine carbon black structure were very dependent upon theprevious history of the sample, that is, by the amount of mechanicalwork performed on the sample prior to the test. The authors reportedthat a direct relationship could be shown between carbon black structureand extrusion shrinkage of the elastomer if the carbon black wassubjected to repeated high pressure compression prior to running thestandard ASTM D24 1 4-6.7T DBP absorption procedure. Accordingly, itbecame desirable for the industry to develop a press which would enablesmall samples of carbon black to I be compressed in the range of 15,000to 30,000 psi.

in order that the sample might be prepared for running the above ASTMDBP absorption test. The utilization of compression prior to determiningthe structure of the black enables the rubber fabricator to predict theeffect of structure on the resulting extrusion shrinkage of therubber-carbon black mixture.

Due to the fact that the compression of a carbon black sample prior torunning the DBP absorption test is to be under laboratory conditions, itwas deemed highly desirable to have a press which could be manipulatedeasily by a laboratory technician wherein repeated pressings could bemade of various samples over a period of time. The laboratory methodsknown at this time utilize apparatus to compress the carbon black sampleinto a pellet or pill form which must be then removed from thecompression cylinder to be brokenand recompressed. The compression,breaking and recompression steps are repeated several times, dependingupon the desired end result. The repeated steps of compressing andremoving the sample from the compressed cylinder, however, expose thesample to risk of loss, dust, dirt, and operator error. Accordingly, itis desired to develop a compact press having the feature of a pelletplunger which eliminates the foregoing problems and enables theoperation of several repeated compressions with intervening breaking ofthe compressed pellet in situ without removal from the cylinder cavity.

I have discovered a compact carbon black press and pellet plungerapparatus which overcomes deficiencies and those of the prior art.Briefly, the apparatus of the invention comprises a cylinder and pistonmounted in a suitable framing device which enables a pressure providingmeans to force'the piston through the internal diameter of the cylinder,thereby compressing ,a carbon black sample which has been placed in thecylinder. The apparatus further provides apellet plunger means forbreaking in situ the pelletized carbon black. The

pellet plunger of the invention resides in the bottom seal plate uponwhich the carbon black sample is compressed. The plate is provided witha handle which allows the operator to easily remove the carbon blacksample after repeated compression and breaking steps. The bottom sealplate is also provided with alignment means on the upper and lowersurfaces thereof which insures that the plate is in proper position inorder to proceed with the pressing of the black. The plate has anopening through the center portion to accomodate a break-up mandrel orplunger which has a stem protruding from the bottom of the seal plateand is held in at-rest position by a spring or related means. Thismodified bottom seal plate-plunger apparatus allows the operator tobreak up the pressed pellet of black after each compression; forexample, by rapping the stem with a mallet after the compression pistonis withdrawn. The compressed pellet which was lying on the polishedsurface of the bottom seal plate is broken up by impact as the plungerrises into. the cylinder chamber as a result of impact upon its stem.The spring or related means retracts the plunger to an at-rest position,and repeated compression may proceed without removing the carbon blacksample from the cylinder. The apparatus of the invention eliminatessample loss, dust, and dirt from the pressing operation and enables asmany compression steps as necessary to be made in situ without removingthe pellet for breaking purposes.

Accordingly, it is an object of this invention of provide a press andpellet plunger which enables repeated compression and breaking ofparticulate or powdered samples. It is a further object of thisinvention to provide a press and plunger means which is designed tocompress and in situ break carbon black pellets prior lowing disclosure,claims and the drawing, wherein the sole FIGURE is a cut-away elevationof the apparatus of the invention.

The press and pellet plunger of the invention and the operation thereofcan best be understood by a detailed description of the drawing.Referring to the drawing, the press of the invention consists of a pairof upstanding sides 2 which are mounted on base 4. Sides 2 are providedwith grooves 9 which enable three cross plates or guide plates to fastenby bolts 3 to the sides 2. The three cross plates are therefore mountedat right angles to sides 2. The upper plate 6 is a pressure providingmeans mounting block which has opening 11 therein and is adapted toreceive the pressure providing means 30. The lower plate 7 is a bottomplate having an opening 12 therein. Plate 8 located intermediate plate 6and plate 7 is a cylinder support means having an opening 13 therein,opening 13 being designed to receive cylinder 15. Cylinder is easilyremovable from the opening 13 in plate 8, and has a circumference of theouter surface at its upper portion greater than the circumference at itslower portion, therefore forming flange 16. The interior bore 14 ofcylinder 15 is continuous throughout the length of cylinder 15.

The lower portion of the cylinder 15 rests upon bottom seal plate 17.Bottom seal plate 17 is conveniently provided with a handle 18 whichprotrudes from the lateral edge of seal plate 17. The seal plate isprovided with a raised portion 19 which has the same geometricalconfiguration as the interior bore 14 of cylinder 15. The lower portionof bottom seal plate 17 is provided with a raised portion 27 which hasthe same geometrical configuration as opening 12 in bottom plate 7. Thebottom seal plate 17 has an opening therethrough which accomodates theplunger 20 having a plunger head 22, and a plunger stem 24. The plungerhead has an upper surface 23 which when the plunger is in apredetermined at-rest position is in registry with the raised portion19. The plunger 20 has a stem 24 and a spring 26 which returns theplunger to a predetermined at-rest position following a motivationstroke on the plunger stem lower end 25, thereby causing the movablypositioned plunger to enter the cylinder bore 14. Cylinder 15immediately below flange 16 is provided with a flexible ring 32 which iscontinuous about the circumference of the outer surface of the lowerportion of cylinder 15 so that when the cylinder is in place in cylinderguide plate 8, the flexible ring contacts the surfaces of opening 13within cylinder guide plate 8. The' flexible ring may be made of naturalor synthetic rubber or plastics; The flexible ring 32 upon cylinder 15assures that proper alignment is maintained during the pressingoperation and provides a limited amount of freedom of motion with regardto the position of cylinder 15 upon the bottom seal plate 17.Accordingly, cylinder 15 has a minimal amount of freedom of movement ina horizontal direction, thereby preventing the piston from scraping thesurface of bore 14.

The interior surface of bore 14 and exterior surface of piston 28 arealigned in such a way that when plunger 31 exerts a downward force, thepiston 28 travels the length of the bore 14. The composition of thecylinder and that of the piston are of certain critical compositionswhich are hereafter explained. The ends of piston 28, at the edgesthereof, are beveled as shown by surface 29. This ensures easy insertionof piston 28 into the bore 14 of cylinder 15.

The raised surfaces 19 and 27 on the seal plate 17 provide a means ofproper alignment of the bottom of cylinder 15 so that the actuation ofcompression plunger 31 against piston 28' to force the piston throughthe length of bore 14 will not gall or freeze the high friction surfacesin the lower portion of bore 14. The raised surfaces also insure thatthe operator of the press may remove and replace seal plate 17 in theproper alignment with respect to cylinder 15. it is to be noted that thedimensions of surfaces 19 and 27 are less than the dimensions of bore'14 and opening 12, This is in accordance with the requirement that thecylinder 15 have limited freedom of movement in a horizontal directionwhich is provided by ring 32. Accordingly, the tolerance between thelateral edge of surface 19 and the surface of bore 14 is greater thanthe tolerance between the lateral edge of 27 and the surface of opening12. In operation, the press of the invention is designed to subject acarbon black sample placed in bore 14 of cylinder 15 to a pressure inthe range of 15,000 to 30,000 p.s.i., preferably 24,000 p.s.i. At thestart of the compression operation, compression plunger 31 will be in aretracted position Piston 28 is then removed from cylinder bore 14,cylinder 15 is removed from opening 13 and the cylinder guide plate 8,and bottom seal plate 17'is removed from the opening 12 in bottom plate7 by means of handle .18. Bore 14 of cylinder 15 may then be cleanedwith a suitable cleaning means, for example, by passing a cloth throughthe bore. The surface of piston 28 may then likewise be cleaned bywiping off the piston. 4

To precompress a sample of carbon black prior to running the ASTMD2414-67T DBP absorption test, the bottom seal plate '17 is placed into opening12 of bottom plate 7 by means of handle 18. The cleaned cylinder is theninserted into opening 13 of cylinder guide plate 8 in such a way that itrests upon bottom seal plate 17 with raised surface 19 of bottom sealplate 17 projecting into the lower portion of bore 14. This assures theproper alignment of the cylinder so that when plunger 31 forces piston28 through the length of bore 14, galling of the surfaces of piston 28and interior bore 14 is prevented.

Twenty-five grams of carbon black sample which is dried at 220F for onehour are then poured into cylinder bore 14. Piston 28 is then insertedinto the upper portion of bore 14 and pushed downward as far as possiblethrough the length of bore 14 of cylinder 15 by hand. The plunger meansis then activated. The lower surface of compression plunger 31 isbrought into contact with piston 28 thereby subjecting the carbon blacksample in bore 14 to a compression of, for example, 24,000 p.s.i. whichis read upon a standard pressure gauge. The pressure is heldapproximately 3 seconds and the plunger activation mechanism isreleased.

The operator then activates the plunger 20 through a compaction meansexerted upon the plunger stem lower end 25, thereby forcing the plungerhead 22 into the bore 14 of cylinder 15 containing the compressed carbonblack sample; The compressed carbon black pellet which was lying on theraised portion 19 of bottom seal plate 17 and upper surface 23 ofplunger head 22, is broken up by impact of the plunger head as it risesinto the cylinder chamber bore 14. The plunger stem spring 26 retractsplunger 20 to a predetermined at-rest position thereby again providing acylinder bore for purposes of compression. The in situ plunger breakin gof the compressed carbon black sample pellet eliminates removel of saidpellet for breaking purposes,

' thereby reducing the posibility of sample loss or contaminationthrough operator error. The aforementioned compression, breaking,recompression, steps can be repeated as deemed necessary according tothe requirements of the compressed sample.

The operator can remove the last compressed pellet which is unbroken orif conditions require, a broken sample, by grasping the upper portion ofcylinder with one hand, lifting it and with his other hand removingbottom seal plate 17 by means of handle 18. When plate 17 is removed,cylinder 15 will rest on cylinder guide plate 8 by means of flange 16.The carbon black sample will usually remain in the bore 14 even thoughthe bottom seal plate 17 has been removed. A small pan is placed uponbase 4 immediately below opening 12 of bottom plate 7. Any carbon blackpresent on surface 19 may be suitably transferred to the pan located onbase 4. The plunger is then once again activated, forcing piston 28throughout the length of bore 14 which causes the majorityof pressedsample to fall into the pan located on base 4. It should be noted thatafter compression the carbon black sample is of relatively looseagglomerates, and even if a pellitized carbon black sample is pressed,the resulting pressed carbon black does not remain in a pill type form.

The overall-dimensions of the press will be generally in the range ofthat which is easily mounted in a laboratory. Accordingly, the overallheight of the press including the compression and plunger means willgenerally be in the range of from 2-V2 to 4 feet in height. The distancebetween the sides 2 will be in the range of from 4 to 10 inches. It isapparent, however, that these dimensions are not critical to design ofthe invention. However, a preferred embodiment of the apparatus of theinvention, particularly in reference to the nature of the surfaces ofbore 14 and piston 28 in order to avoid galling or freezing require aRockwell hardness of a metallic surface which is determined by ASTMProcedure El8-6l. The surface of bore 14 and the surface of piston 28must be different. Accordingly, the piston may be made of any metal ormetal alloy conventional in the art; however, it must have a Rockwellhardness in the range of 50 to 70C, preferably 60C. The interior surfaceof bore 14 may also be made of any conventional metal or metal alloydifferent from the material of the piston wherein a Rockwell hardness of20 to 45C, preferably 28 to 30C, is provided. A second preferredspecification which is deemed adequate to insure operation of the pressis that the diameter of piston 28 must be in the range of 0.0015 to0.0035 inch less than the diameter of bore 14 of cylinder 15.Preferably, the diametral clearance between the surface of piston 28 andthe surface of bore 14 is in the range of 0.0024 to 0.0025 inch. Whenthese specifications are met, the activation of plunger =31 upon thesurface of piston 28 insures that the piston will travel the length ofbore 14 without galling thesurface of the piston or that of bore 14 ofcylinder 15. These specifications also insure that the carbon blacksample pressed in bore 14 will not bleed excessively into the clearancebetween piston 28 and bore 14.

A third preferred embodiment of the'invention requires that the plungerhead 22 be in register with the raised surface 19 of bottom seal 17thereby providing a polished-like surface. In order to provide thepolished-like surface, the plunger head 22 when at-rest position throughthe action-of plunger stem spring 26, must be slidably positioned in thebottom seal opening 21 in order to accomodate the plunger head 22 andthe plunger stem 24.

Other modifications and variations of the invention are possible withoutdeparting from the spirit and scope of the invention. In particular, itis possible to utilize the apparatus for pressing particulate typematerials other than carbon black. Furthermore, it is within the scopeof the invention to modify the shape of the piston 28 and bore 14;however, a cylindrical configuration is preferred.

What is claimed is:

1. A press conprising:

a hollow cylinder adapted to receive particulate material to becompressed; a piston positioned for movement through said cylinder toexert a force on material in said cylinder;

means to exert a force on said piston to cause movement thereof throughsaid cylinder toward one end of said cylinder .to compress theparticulate'material;

a plate positioned across said one end of said cylinder, said platehaving an opening therethrough in alignment with the opening throughsaid cylinder;

a plunger having a head and stem and positioned for 4 movement throughthe opening in said plate, said plunger stem being positioned to extendbeyond said plate on the side thereof remote from said cylinder so thatan external force exerted on the end of said stem displaces the head ofsaid plunger into said cylinder for breaking said compressed particulatematerial within said cylinder; and

means engaging said plunger to exert a bias force thereon which normallypositions said plunger so that the head end thereof is flush with andlocated at the surface of said plate which is adjacent said cylinder inthe absence of an external force being exerted on said stem end of saidplunger.

2. The press of claim 1 wherein said plunger head is of greater diameterthan said plunger stem, and the opening in said plate is provided with ashoulder on which said plunger head normally rests.

3. The press of claim 2 wherein said means to exert a bias forcecomprises a spring secured to the stem end of said plunger and extendingtherefrom to engage said plate so as to exert a force which normallyretains said plunger head on said shoulder.

1. A press conprising: a hollow cylinder adapted to receive particulatematerial to be compressed; a piston positioned for movement through saidcylinder to exert a force on material in said cylinder; means to exert aforce on said piston to cause movement thereof through said cylindertoward one end of said cylinder to compress the partIculate material; aplate positioned across said one end of said cylinder, said plate havingan opening therethrough in alignment with the opening through saidcylinder; a plunger having a head and stem and positioned for movementthrough the opening in said plate, said plunger stem being positioned toextend beyond said plate on the side thereof remote from said cylinderso that an external force exerted on the end of said stem displaces thehead of said plunger into said cylinder for breaking said compressedparticulate material within said cylinder; and means engaging saidplunger to exert a bias force thereon which normally positions saidplunger so that the head end thereof is flush with and located at thesurface of said plate which is adjacent said cylinder in the absence ofan external force being exerted on said stem end of said plunger.
 2. Thepress of claim 1 wherein said plunger head is of greater diameter thansaid plunger stem, and the opening in said plate is provided with ashoulder on which said plunger head normally rests.
 3. The press ofclaim 2 wherein said means to exert a bias force comprises a springsecured to the stem end of said plunger and extending therefrom toengage said plate so as to exert a force which normally retains saidplunger head on said shoulder.